Literary usage of Countermortar fire

Below you will find example usage of this term as found in modern and/or classical literature:

1.Howard's Hill and Other True Stories: Small Unit Marine Action in Vietnam by DIANE Publishing Company (1990)"The countermortar fire silenced the enemy weapon. During that exchange, Sullivan
took shrapnel in the leg. It slowed him down but did not impede his ..."

2.The Military Dictionary (1987)"... countermortar fire. See also fire. counterforce—(DOD) The employment of
strategic air and missile forces in an effort to destroy, or render impotent, ..."